Cherkin 1998.

Methods	Randomised, controlled, concealed allocation, and intention‐to‐treat basis. No blinding.
Participants	Adults with LBP for 7 days. Total participants eligible for the study was 323. After excluding 2 participants, the further intervention and analysis were performed on the following distribution: Booklet group, N = 66; Chiropractic group, N = 122; Physical therapy group, N = 133; Inclusion criteria: all who did not meet exclusion criteria. Exclusion criteria: mild or no pain 7 days after the visit to the physician, history of back surgery, sciatica, or severe concurrent illnesses. 169 men and 154 women, mean age 41 years in exercise group, 40 years in both Chiropractic manipulation group and control group.
Interventions	Exercise group: Subjects received McKenzie exercise class by physiotherapists within four days after randomisation for first visit and up to eight more visits. Patients received a self‐learning book and a lumbar cushion. Chiropractic manipulation group: Subjects received chiropractic manipulation by chiropractors within four days after randomisation for first visit and up to eight more visits. Chiropractors could suggest exercises and activity restriction as their usual practices. Minimal‐intervention control group: Subjects received an educational booklet only.
Outcomes
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	After baseline assessment, subjects were randomly assigned without stratification.
Allocation concealment?	Low risk	Adequate, the use of sealed and opaque envelopes.
Blinding? All outcomes	High risk	No blinding reported.
Incomplete outcome data addressed? All outcomes ‐ drop‐outs?	Low risk	Between 89 and 96 percent of the subjects responded to the follow‐up questionnaires.
Incomplete outcome data addressed? All outcomes ‐ ITT analysis?	Low risk	ITT was used to address the loss of follow‐up outcomes.
Similarity of baseline characteristics?	Low risk	Most baseline characteristics were similar except that subjects in the physical therapy group had more bothersome symptoms and subjects in the educational‐booklet group reported fewer days with restricted activity.
Co‐interventions avoided or similar?	Low risk	The reported use of exercise was almost identical in all groups at baseline and 1 month.
Compliance acceptable?	Low risk	Around 96 percent of the subjects complied with their assigned visits to the care provider at least once.
Timing of outcome assessments similar?	Low risk	Outcomes were assessed 1, 4, 12, 52 and 104 weeks after the beginning of study in all groups.